The ONL Tutorial

Course Material >> Exercises TOC

Basic Queueing Exercises

Topics in this section include basic queueing effects, traffic generation, and more traffic monitoring.

IMPORTANT NOTE: Throughout the exercise descriptions, interface names that begin with a dollar sign (e.g., $n1p2, $n2p3, $n3p1a) refer to the Ethernet interface that is connected to the control network. Recall that every host has two interfaces: one to the internal (private) testbed network and one to the external (control) network. Experimental traffic goes over the internal network consisting of your NSPs and the interconnection switch. Control messages and SSH access to a host from onl03 go over the external (control) network. Interfaces to the internal network have IP addresses of the form 192.168.N.H where N is the NSP number and H is the host portion and have names such as n1p2, n2p3 and n3p1a (note no dollar sign). Interfaces to the external (control) network have IP addresses of the form 128.252.153.H where H is the host portion and have names such as onl21.arl.wustl.edu. These external names are determined during the commit phase when actual resources are bound to resources in your configuration.

You can determine the external interface names by right clicking on a host icon. But in many cases (especially scripts), it might be easier to refer to the environment variable (e.g., $n1p2) associated with the external interface. These variables can be imported into your environment by running one of these two commands: 

     source ~onl/.topology		# bash
     source ~onl/.topology.csh		# csh
You can verify that this procedure works by enterring something like: 
     printenv n1p2
     echo "$n1p2"
which should display an external name of the form onlXX.arl.wustl.edu in both cases.

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Course Material >> Exercises TOC